L2 - PHYTOPLANKTON

Question 1

PHYTOPLANKTON FACTS

• MAKE UP 45% of global primary production
• Produce 70-80% of global oxygen
• Form the basis of alot of food chains

(Phytoplankton > Zooplankton > Fish > Sharks/Mammals)

Question 2

Phytoplankton / Micro-algae

Algae = Eu-kary-otes:

Possessing both a nuclear membrane and membrane-bound organelles.

Cyanobacteria = Pro-kary-otes:

Lack a nuclear membrane and membrane-bound organelles.

Question 3

Micro-Algae Origins

Single celled protists ‘captured’ cyanobacteria

They then evolved into organelle (chloroplast = phytosynthesis)

*Endosymbiosis

Question 4

THREE DOMAINS OF LIFE

- EUKARYOTA

Dinoflagelates (protista)

Red Algae (Protista)

Protists with flagella

- EUBACTERIA

Cyanobacteria

(Blue/Green algae)

- ARCHAEA

*Protists - Organisms which are unicellular or unicellular-colonial and which form no tissue.

Animals and fungi more alike than protists.

Eukaryotic algae and cyanobacteria different kingdoms

Question 5

Classification of Algae

Kingdom: Bacteria

Cyanobacteria (Blue/Green)

kingdom: Protista - Eukaryotic algae

Chlorophyta (green algae)

Bacillariophyta (diatoms)

Euglenophyta (euglenoids)

Dinophyta (dinoflagellates)

Question 6

Chlorophyta (Green Algae)

• Abundant in freshwater
• Contain chlorophylls -a and -b
• Store photosynthetic product as starch
• Cellulose (mostly glucosamine) cell walls
• ‘Evolutionary bridge’ that gave rise to land plants

Answer 6

Chlorophyta Reproduction

Asexual reproduction

Sexual reproduction

• Fusion of identical cells (isogamy)
• Fertilisation of a large non-motile cell by a smaller motile one (oogamy)

Question 7

Red Waikato Lakes = Chlorophyta

Culprit was identified as Mono-rap-hidium sp,

Reasons for bloom?

Some species produce corotnoids during times of their lifecycle which gives them a red colour and masks out the green chlorophyll colour.

Question 8

Bacilla-rio-phyta (Diatoms)

• Abundant in freshwater and marine environments (ca. 100,000 species).
• Extremely environmentally sensitive > useful for assessing health of aquatic systems.
• Mass sedimentation events can occur with a rapid change from turbulent to stratified conditions.

DIATOMS

Diatoms are single-celled algae.

Diatoms are algae that live in houses made of glass.

They are the only organism on the planet with cell walls composed of transparent, opaline silica.

Diatom cell walls are ornamented by intricate and striking patterns of silica.

• Diatom cell wall is heavy because of silica, therefore they rely on sitting on the benthos or if they’re planktonic they rely on turbulence to keep them up. If movement stops like in a stratified system those diatoms can no longer keep themselves up where they just sink down the water collumn (how deep ocean ecosystems get their food supplies).

Question 9

Two types of Diatom

Centric diatom (circular)

Pennate diatom (oval)

Answer 9

Diatom structure

Frustule

• Siliceous cell wall of diatoms, composed of two valves

Valve

- A structual component of the diatom frustule. Two valves fit together to form (along with associated girdle bands) a frustule.

Girdle band

Question 10

Diatom reproduction

a sexual and sexual reproduction

(Sexual reproduction has advantage as it leads to population diversity with the two pools of DNA)

A. Diatom with smaller valve faces the problem. When the diatoms reproduce the two valves get oushed apart my two new forming cells. Another valve forms and its no worry for the bigger valve. The smaller valve however grows its new one on the inside and every time it reproduces it gets smaller and smaller and eventually there is not enough room to fit DNA inside anymore.

There is an extra stage in sexual reproduction where an auxospore allows them to grow the valves back to original size so they can start again with A sexual reproduction.

Question 11

Didymosphenia geminata (Didymo)

“Good example of Diatoms around NZ = Didymo. Water in North Island to much nutrients for Didymo to grow in, South Island however has low nutrient levels which is ideal for EPS growth”

First ever described Diatom (1980 Scotland)

Each cell produces maddive amounts of extracellular polymeric substances (EPS)

It is the EPS production responsible for negative imapcts

Very low nutrient rivers

Answer 11

Didymo Impacts

Ecological impacts

• Perhaps relatively modest ecological effects?
• Evidence of shift to smaller macroinvertebrates

Aesthetic / Nuisance

No significant health risks

Economic Impacts

• Block water intakes / screens (hydro and irrigation)
• Tourism
• Recreational fishing industry

Question 12

Eu-gleno-phyta

Single celled

One large visible flagellum

Mostly freshwater

Metabolic energy aswell as photosynthesis

Light sensitive eyespot (stigma)

Reproduce asexually (primitive)

Question 13

Dinophyta (Dinoflagellates)

2 flagella used for swimming (whirling motion)

Cellulose plates

Can be armoured (spines)

Contains chlorophyll a & c and peridinin (chlorophyll protien used in photosynthesis)

Answer 13

• A sexual cell division
• Sexual reproduction
• Two dinof join (planozygote)
• Resting spores (hypnozygote) survive in sediment/ballast water
• Favourable conditions > Germinates forming planomeiocyte

Example of DF in the waikato is the Ceratium hirundinella which produce a red bloom

Question 14

Four Key Phyla?

A.

B.

C.

D.

?

Answer 14

A. CHLOROPHYTES

B. DINOFLAGELLATES

C. DIATOMS

D. EUGLENOIDS

Question 15

What is production?

‘The total or relative rate of carbon accumulation’

(the ability to take organic carbon and convert it to an organic useable form)

Answer 15

Controls on Photosynthesis

Nutrient Supply

Macro nutrients: CO2 - NO3 - NH4 - PO4

Micro nutrients: Fe - Mo - etc.

Availability of light

(Photosynthetic available radiation)

Temperature